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Stow Agricultural Commission

Stow, Massachusetts

Right-to-farm Bylaw
Property Notification

Management of late blight

Most Stow farms and gardeners had problems in 2009 with late blight on tomatoes. Another, limited outbreak occurred in 2012. Late blight is a fungus that spreads by spores, which can travel easily through the air from infected plants. Late blight also attacks potatoes and is the historical cause of the Irish Potato Famine (c. 1845-1852). The UMass Extension has a newsletter, and the June 24th 2010 issue has a section on tomato blights. It can be found here. It includes photographs that will help identify various diseases of tomato, such as early blight, late blight, and Septoria leaf spot. The newsletter says "It is important to recognize the seriousness of the risk that we face, but it is also important not to panic! The information in this week’s newsletter is designed to help you distinguish what IS and IS NOT late blight, decide when and how to protect your crops, and to use the strategies that have worked in other regions that are regularly affected by this disease."

More photographs can be found here showing characteristics of late blight and differences from early blight.

Another paper describing things that will reduce the likelihood of late blight is available from Johnny's Selected Seeds, in Albion, ME. It can be found here.

Cornell University has a website with late blight information and photos for identification. They also have a reference paper for gardeners

A national website has been set up to track occurrences of late blight. It can be found at The website has a map that shows confirmed reports by county.

last update 2013 June 23